OFFSET
0,5
COMMENTS
FORMULA
PE=exp(matpascal(5))/exp(1); A = PE^3; a(n)= A[ n,4 ] with exact integer arithmetic: PE=exp(matpascal(5)-matid(6)); A = PE^3; a(n)=A[ n,4]
E.g.f.: (x^3/6) * exp(3 * (exp(x) - 1)). - Ilya Gutkovskiy, Jul 11 2020
MAPLE
A056857 := proc(n, c) combinat[bell](n-1-c)*binomial(n-1, c) ; end: A078937 := proc(n, c) add( A056857(n, k)*A056857(k+1, c), k=0..n) ; end: A078938 := proc(n, c) add( A078937(n, k)*A056857(k+1, c), k=0..n) ; end: A129329 := proc(n) A078938(n+1, 3) ; end: seq(A129329(n), n=0..27) ; # R. J. Mathar, May 30 2008
MATHEMATICA
A056857[n_, c_] := If[n <= c, 0, BellB[n - 1 - c] Binomial[n - 1, c]];
a[n_] := A078938[n + 1, 3];
a /@ Range[0, 20] (* Jean-François Alcover, Mar 24 2020, after R. J. Mathar *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gottfried Helms, Apr 08 2007
EXTENSIONS
More terms from R. J. Mathar, May 30 2008
STATUS
approved